A. Field of the Invention
This invention relates to electrical timing apparatus or the like and, in particular, to an all-electronic timing device in which both the timing cycle and the choice of several timing ranges is accomplished with a single knob.
B. Prior Art
In the past, timers having multi-range features, such as the Model 328 Timer marketed by the Automatic Timing & Controls Company of King of Prussia, Pa., employed two knobs for controlling, respectively, the range and the length of the timing cycle within a specified range.
To the extent that there was sufficient room to position the two knobs of the two-knob timers so that they were easy to manipulate manually, two-knob timers were useful. However, it is sometimes desired to make a small timer, such as the present timer, in which case placement and normal manipulation of two knobs is very difficult. Also, even without that disadvantage, two-knob timers are often more expensive to manufacture than a single knob timer as taught in the present invention.
Other available timers had a dial for indicating the progress of the timing cycle and a screw driver adjustment by which an operator of a process could change the range. With this kind of timer, while it was possible to change the range and show what that range was, the dial on which the timing indicia appeared remained unchanged. Thus, it was necessary to make a mental interpolation for proper placement of the decimal point on the dial when a range was brought into play which was a multiple or submultiple of the range for which the dial was meant to be read directly.
It is therefore among the objects of the present invention to provide:
1. A single-knob timing apparatus in which manipulation of the knob changes both the range and the length of a particular timing cycle.
2. A timer having a single knob for (a) allowing selection of a particular timing cycle (b) selection of the range and (c) simultaneously changing the dial presentation to accord with the range chosen.
3. A timer which may be made smaller because it has a single knob used to perform a plurality of functions.
4. A timer which is less expensive to manufacture than many other known timers.
5. Apparatus having a single knob which, depending upon its axial position, can control a plurality of operations as a function of its axial position.
6. Apparatus having a single knob which, in addition to performing a number of operations as a function of its axial position, can simultaneously present a visual indication of each function being performed.